Prevalence of urolithiasis in Kaizuka City, Japan--an epidemiologic study of urinary stones.

BACKGROUND

According to the results of nationwide surveys, the prevalence of urolithiasis has been steadily increasing in Japan. However, these surveys relied on hospital statistics, and there has been no survey of the prevalence of urolithiasis in Japan utilizing postal questionnaires. We surveyed the prevalence of urolithiasis among the inhabitants of Kaizuka City.

METHODS

A total of 3,000 inhabitants ranging from 20 to 59 years old were randomly selected from the census register in numbers consistent with the population distribution of each district and sex by municipal computerized system.

RESULTS

A total of 1,975 postal questionnaires were returned, and 1,972 (65.7%) were considered valid. Of the respondents, 137 (6.95%) had a history of stones (men; 9.64%, women; 4.51%). The annual incidence of urolithiasis for Kaizuka citizens aged from 20 to 59 years old in 1991 was 0.97%, and the lifetime prevalence of urolithiasis increased linearly with age, and it was 10.3% for respondents in their 50s. In the total survey population of 7,568, which included the respondents and their family members, 342 (4.52%) had a history of stones. Male administrative workers had a significantly higher prevalence than any other occupational group. The monthly expenditure on food by the families of stone formers was significantly greater than that by the families of non-stone formers.

CONCLUSION

Extrapolation of the findings suggests that > 10% of the general population (> 13% of men and > 7% of women) can be expected to suffer from urolithiasis at least once in their lifetime.